The considerable variation in American fertility during the past few decades has been the subject of a number of important national studies. They have documented the role of the growing adoption of more modern birth control methods in the recent fertility decline. However, further research is still called for on why Americans want and have the number of children they do. One promising lead in the explanation of this fertility decline has been theories which focus on the utility of children versus competing allocations of time and other resources. Specifically, recent research has demonstrated a relationship between alternative modes of sex role behavior and fertility, while noting that longitudinal studies are needed to elaborate the nature of this relationship. The population for the proposed panel study consists of 9,650 freshmen women from a national sample of 45 colleges who were surveyed in 1964. That portion of the population that can be located through their college alumni offices, plus a subsample of their husbands, will receive a mailed questionnaire designed to ascertain current parity and expected fertility as well as career involvement and other aspects of sex role modernity. We anticipate between 1250 and 2500 usable questionnaires.